Grinding device



April 10, 1934.

' G. PEARSON enmnim DEVICE Filed Nov. 11, 1929 IA'VE/VTOR Geo. Pearson W 47 A TTORNEY Patented Apr. 10, 1934 UNITED STATES PATENT OFFICE 1,954,575 GRINDING navrca George Pearson, Salt Lake City, Utah Application November 11, 1929, Serial No. 406,391 2 Claims. (CL 51-- 1'l0) This invention relates to a grinding device, and more particularly to one which is electrically driven and is especially adapted to grinding the breaker points of the ignition system of'an internal combustion engine,'and has among its objects:

To construct a device of the kind specified which shall be simple and cheap to construct yet rapid and eflicient in operation,

To invent a grinder which may be operated by current from the battery of an automotive vehicle or other circuit; or from a light circuit.

To prevent sparking at the change of ,the current from one coilto the other; To construct a device of the kind named which will properly grind the said points to allow for thearcuate movement of one. of them yet insure perfect contact;

To devise such a device which will permit of its being held at an angle to the desired surface, yet will not form such surface with an improper relation to the rest of the point.

The-satisfactory operation of an internal combustion engine depends to a great extent upon the breaker points of the ignition system meeting with a full face to face contact, and the pitting of such points by the heat of the spark at each break makes it necessary that such points be ground frequently. When this grinding is done by hand it requires either the removal of the points, or else takes a long time to do a job which may not be satisfactory when finished, due to the fact the faces formed on said points are not accurately in full contact over all-their surfaces. The; present invention makes it possible to perform this operation rapidly and accurately.

Fig. 1 is a longitudinal sectional view of the assembly of this device;

Fig. 2 is a top plan view with the cap removed;

Fig, 31s a plan view of apart of the magnetic circuit;

Fig. 4 is an" elevational member;

Fig. 5 is a transverse section of the armature on the line 55, Fig. 1;

Fig. 6 is an edge elevation of the abrasive element;

Fig. 7 is a crosssection of the saidelement'on the line 7-7, Fig. 1;

Fig. 8 is a diagram of the circuits in ils device.

Coils 9 and 10, connected in series, arcmounted onan insulating sleeve 11 with an iron shell 12 enclosing them, and an iron spacer 13 between their adjacent ends. An armature 14' is reciprocably mounted inside sleeve '11 upon a shaft 15,

view of a bracket netic circuits. The aforementioned coils, spacer,

and polepieces may be retained in shell 12 by suitable fastening means, such as screw 24, or the said shell may be pressed thereon tightly enough to hold them in place.

A plate 25 of insulating material is secured to the outer face of polepiece 21, and on it are mounted brackets 26 with upstanding ears 2'1 and 28, said ears having oppositely facing notches 29 and 30, respectively, cut therein. A yoke 31 is fixed to the upper end of shaft 15 by means of nut 32, said yoke being of non-conducting substance; holes 33 are formed through yoke 32, and through each of said holes is passed a spring 34, one end of each of said springs being attached to an ear 27 and the other end being attached to a vibrator 35. Secured on plate 25 by screw 36 is an insulating spacer 37 and on this is a metal support 38 which carries point 39, on said supportis a second insulating spacer 40, on this is a second metal support 41 which carries point 42, and on this is an insulating washer 43. Points 39 and 42- are adapted to contact points 44 and I 45 on vibrator 35. Wire 46 is connected to metal support 41 and to a source 47 of electric current, while wire 48 is connected to the other terminal of said source and to support 38; said vibrator 35 is also connected to the junction 49 of co 9 and 10, by a wire 50.

The lower end of shaft 15 carries an abrasive a desirable and necessary degree of flexibility,

enablingrthe proper operation of the abradlng 'element even though the tool may not be held perpendicular to the work. The foregoing element 51 is thicker at oneside 53 than at the other side 54, said variation in thickness being such that said element is part of a sector of thecircle which is described in part by the swing of the movable point of the breaker of the ignition sys- 26 wardly; the resistance of wire 50, 'etc., being less tom, so that'the proper bevel will be imparted to the points of said breaker when said element.

511s placed therebetween with the edge 53 at the radially outer side of said points, with referenceito the arcuate swing of said movable point.

Coupling 52 readily detachable from shaft 15 to permit the use of abrasive elements of different degrees ofvcoarsenes's, and is flexible to allow shaft15 to be held'obliquely tothe faces to be formed on the points being ground without mak' 'ing said faces also oblique to the desired plane of the faces. I Operation Starting with the parts of the device in the positions shown in Figs. 1 and 8, for example, the

47, energizing coil ,9 and drawing armature 14- with the attached shaft 15 and'element 51 upthan that of 'coil 10 the current-willfollow this path. At the upper limit of movement ofshaft springs will snap point 45 into contact with point 42, thus closing the circuit through wire46, points 1 42 and 45, wire 50, coil 10, and wire 56 back to battery 47, energizing coil 10, and drawing armature 14, shaft 15, and element 51 down, the yoke 31 and springs .34 acting to snap vibrator 35' down so that points.44 and 39 are again in contact.

- It will be observed that-at no time is there a breaking of the circuit, which would cause a destructively hot spark at such break and soon destroy points 39, 42, 44 and 45; when vibrator 35 is in such position that the points carried are not'in contact with either of points 42 or 39 there is a closed circuit through-wires 46', 55, coils 9 and 10, and wires 56 and 48, so-that it is unnecessary to use acondenser to prevent the hot spark at break which-would otherwise occur.

Edges 57 at the extremities of vibrator 35 are disposed in the notches-30 of' ears 28, and so form a frictionless support for said vibrator, and thus shaft 15 can be rapidly oscillated by the changes 8 .in energizationof coils 9 and 10, and the grind-,

in'g'of .the breaker points be expeditiously effected "by element 51 while said points are in place, thus saving the time and expense of removing them.- Members 20 and. 21, and spacer 13, act as pole-' piecesto-attract armature 14, and serve also to form a magnetic .path of low reluctance between the ends of coils 9 and 10, in conjunction with shell 12; There is no change in thedirection of flow of the lines of magnetic force, so that there is. no energy consumed in sweeping out. opposed residual-magnetism in any part of the magnetic circuit. 4 The members lfijbeing'of rubber, not only secure armature 14 upon shaft15, but serve as resilient bumpers at the extremes of movement thereof, and, their rebound starts the reverse movement of the said armature. 15 the thrust of-yoke 31 against springs 34 will .draw vibrator 35, up, and the tension of said 2. A device for dressing breaker points, comprising a thin abrasive element, a reciprocable member, a rubber connection between said element and said member, and an electromagnetic device to reciprocate said member.

I GEORGE PEARSON. 

